A high heat-resistant low-dielectric polyimide material and preparation method thereof

Abstract

The present invention relates to the technical field of polyimide materials, specifically a kind of high heat-resistant low dielectric polyimide material and its preparation method. The present invention first uses 4-aminostyrene and 1,1,3,3-tetramethyldisiloxane as raw materials, and reacts to obtain siloxane diamine monomer; using hexafluorobenzene and 2,4-diaminophenol as raw materials, reacting to obtain fluorine-modified diamine monomer; Siloxane diamine monomer and fluorine-modified diamine monomer are reacted with biphenyltetracarboxylic acid dianhydride respectively, and amine-terminated silicon-containing oligomers and anhydride-terminated fluorine-containing oligomers are prepared; The oligomers terminated by the two groups are polymerized to obtain a polyimide material containing a silicon-oxygen bond in the main chain and a fluorine element in the side group. The polyimide prepared by the present invention has good dielectric properties and heat resistance, and can be applied to thin circuit substrates for high-frequency and high-speed communications.

Description

Technical Field

[0001] The invention relates to the technical field of polyimide materials, in particular to a high-heat-resistant and low-dielectric polyimide material and a preparation method thereof. Background Art

[0002] Polyimide is a polymer material containing an imide ring in the main chain. It has good mechanical properties, heat resistance and solvent resistance, and is therefore used in aerospace, microelectronics, automotive industry and other fields. At present, electronic products are developing in the direction of lightweight, miniaturization and portability; at the same time, faster computing and communication speeds have become the current demand, so it is necessary to develop thin circuit substrates for high-frequency and high-speed communications.

[0003] In order to achieve high-frequency and high-speed communication, the material needs to have good insulation and heat resistance. Generally, the insulation of a material is related to the dielectric constant. The lower the dielectric constant, the better the insulation performance maintained at high frequency. However, the performance of conventional polyimide is difficult to meet the requirements of maintaining insulation in high-frequency communication. Therefore, it is necessary to develop a high-heat-resistant and low-dielectric polyimide material to meet the application in high-frequency and high-speed communication electronic equipment. Summary of the invention

[0004] The object of the present invention is to provide a high heat-resistant and low-dielectric polyimide material and a preparation method thereof, so as to solve the problems raised in the above background technology.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions: a high heat-resistant and low-dielectric polyimide material and a preparation method thereof, comprising the following steps:

[0006] Step 1:

[0007] S11: Disperse 4-aminostyrene in tetrahydrofuran, use an isopropanol solution of chloroplatinic acid as a catalyst, add 1,1,3,3-tetramethyldisiloxane under an argon environment, raise the temperature to 50-55° C. to react for 3-4 hours, evaporate the solvent, add methanol to precipitate, filter and dry to obtain a siloxane diamine monomer;

[0008] S12: adding biphenyltetracarboxylic acid dianhydride to N,N-dimethylacetamide, adding siloxane diamine monomer, raising the temperature to 60-80° C. in a nitrogen environment, reacting for 2-4 hours, and obtaining an amine-terminated silicon-containing oligomer;

[0009] Step 2:

[0010] S21: Disperse 2,4-diaminophenol dihydrochloride in N,N-dimethylacetamide, add triethylamine, stir until no bubbles are generated in the system, add hexafluorobenzene, calcium hydride, and cesium fluoride, heat to 75-85° C. in a nitrogen environment, and stir to react for 24-30 hours; after the reaction is completed, cool naturally, pour the reaction solution into deionized water, stir, wash, and dry to obtain a fluorine-modified diamine monomer;

[0011] S22: adding biphenyltetracarboxylic acid dianhydride to N,N-dimethylacetamide, adding fluorine-modified diamine monomer, heating to 60-80° C. in a nitrogen environment, reacting for 2-4 hours, to obtain anhydride-terminated fluorine-containing oligomer;

[0012] Step 3:

[0013] In a nitrogen environment, anhydride-terminated fluorine-containing oligomer and amine-terminated silicon-containing oligomer are mixed and reacted for 12 to 24 hours; acetic anhydride is used as a chemical imidization agent and triethylamine is used as a catalyst, and the reaction solution is obtained after stirring for 36 to 48 hours; the reaction solution is coated on a glass plate, and after heat treatment, it is placed in deionized water and demolded to obtain a polyimide material.

[0014] Furthermore, in S11, 4-aminostyrene and 1,1,3,3-tetramethyldisiloxane are reacted at a molar ratio of 2:1.

[0015] Furthermore, in S12, the siloxane diamine monomer reacts with biphenyltetracarboxylic dianhydride in a molar ratio of 1:(0.5-0.95).

[0016] Furthermore, in S21, the amount of each component used, by weight, is 3.5 to 4.2 parts of 2,4-diaminophenol dihydrochloride, 50 to 60 parts of N,N-dimethylacetamide, 5 to 8 parts of triethylamine, 4.2 to 4.8 parts of hexafluorobenzene, 3 to 3.5 parts of calcium hydride, and 3.6 to 4 parts of cesium fluoride.

[0017] Furthermore, in S22, biphenyltetracarboxylic acid dianhydride and fluorine-modified diamine monomer are reacted in a molar ratio of 1:(0.5-0.95).

[0018] Furthermore, in step 3, the molar ratio of anhydride to amine is controlled to be 1:1 to mix the anhydride-terminated fluorine-containing oligomer and the amine-terminated silicon-containing oligomer.

[0019] Furthermore, in step 3, the heat treatment method is 100°C for 1 to 2 hours, 150°C for 1 to 2 hours, 200°C for 1 to 2 hours, and 250°C for 1 to 2 hours.

[0020] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: the present invention provides a method for preparing a polyimide material. Compared with conventional techniques, the polyimide material prepared by the present invention has higher heat resistance and lower dielectric constant. Different from conventional single modification, the present invention simultaneously modifies the main chain and side groups of polyimide, specifically:

[0021] When preparing the polyimide material, 4-aminostyrene and 1,1,3,3-tetramethyldisiloxane are first used as raw materials, the molar ratio of the two is controlled to be 2:1, and a siloxane diamine monomer is obtained through the addition reaction of a carbon-carbon double bond and a silicon-hydrogen bond; hexafluorobenzene and 2,4-diaminophenol are used as raw materials, and a fluorine-modified diamine monomer is obtained through the reaction of fluorine and phenolic hydroxyl groups; the siloxane diamine monomer is reacted with biphenyltetracarboxylic acid dianhydride, and the molar ratio of the two is controlled to be 1:(0.5-0.95) to obtain an amine-terminated silicon-containing oligomer; biphenyltetracarboxylic acid dianhydride is reacted with fluorine-modified diamine monomer, and the molar ratio of the two is controlled to be 1:(0.5-0.95) to obtain an anhydride-terminated fluorine-containing oligomer; the two groups are polymerized according to the molar ratio of anhydride group to amine group of 1:1, and the polyimide material containing silicon-oxygen bonds in the main chain and fluorine elements in the side groups is obtained.

[0022] Among them, the silicon-oxygen bond has high binding energy and stable properties. The introduction of silicon-oxygen bonds in the main chain of polyimide can significantly improve the heat resistance of the polymer, allowing it to maintain a complete structure and stable performance under high temperature conditions; at the same time, silicon-oxygen bonds can improve the usual electrical insulation properties of the polymer and reduce the dielectric constant of the polyimide material; the presence of silicon-oxygen bonds gives polyimide a certain flexibility and improves the processability of polyimide. After the introduction of fluorine-containing groups in the side groups of polyimide, the fluorine element has strong electronegativity and low atomic polarizability. At the same time, the large steric hindrance of the fluorine-containing group can increase the free volume to a certain extent; after the introduction of fluorine-containing groups, the dielectric constant of polyimide is greatly reduced. Both fluorine and silicon elements can improve the hydrophobicity of the material, which is conducive to the material maintaining good dielectric properties.

[0023] In addition, it is necessary to explain that the introduction of flexible siloxy groups into the main chain or fluorine-containing groups into the side groups will increase the linear thermal expansion coefficient of the material. However, experiments have shown that after the two are modified together, the linear thermal expansion coefficient of the material is reduced compared with the single modification. The reasons are as follows: the thermal expansion of polymers is mainly due to the increase in the molecular vibration amplitude caused by the thermal motion inside the molecules after the temperature rises. This thermal motion leads to an increase in the average distance between molecules, resulting in expansion; a single modification often leads to the uniformity of the molecular thermal motion direction and molecular vibration amplitude, so the thermal expansion phenomenon is obvious; while the movement direction of the side group and the main chain are modified at the same time, the movement direction of the side group group is different from the thermal motion direction and vibration frequency of the main chain group. During the thermal motion process, the intermolecular force has changed significantly compared with the single modification. The thermal motion of the side group molecule and the main chain molecule restricts each other to a certain extent, reducing the molecular vibration amplitude, thus reducing the thermal expansion coefficient. The amine-terminated silicon-containing oligomer and the anhydride-terminated fluorine-containing oligomer prepared by the present invention both contain biphenyltetracarboxylic dianhydride, which improves the compatibility of the two to a certain extent; at the same time, the molecular weights of the two oligomers can be adjusted as needed to obtain different chain segments and prepare polyimide materials with different properties; the two oligomers are reacted by block copolymerization to prepare polyimide, and compared with random copolymerization, the chain segment sequence arrangement is more regular and orderly, the intermolecular force is stronger, and the linear thermal expansion coefficient is lower. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0025] Figure 1 It is a schematic diagram of the synthesis route of siloxane diamine monomer;

[0026] Figure 2 Schematic diagram of the synthetic route of fluorine-modified diamine monomers. DETAILED DESCRIPTION

[0027] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] Materials used in the present invention and their sources: The materials used in the present invention are all from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0029] Embodiment 1: A method for preparing a high heat-resistant and low-dielectric polyimide material, comprising the following steps:

[0030] Step 1:

[0031] S11: 4-aminostyrene was dispersed in tetrahydrofuran, an isopropanol solution of chloroplatinic acid (chloroplatinic acid concentration was 0.02 g / mL) was used as a catalyst, 1,1,3,3-tetramethyldisiloxane was added under an argon environment, the temperature was raised to 50°C for reaction for 3 hours, the solvent was evaporated, methanol was added for precipitation, and the siloxane diamine monomer was obtained by suction filtration and drying, wherein the molar ratio of 4-aminostyrene to 1,1,3,3-tetramethyldisiloxane was 2:1;

[0032] S12: adding biphenyltetracarboxylic acid dianhydride to N,N-dimethylacetamide, adding siloxane diamine monomer, heating to 60° C. in a nitrogen environment, reacting for 2 hours, to obtain an amine-terminated silicon-containing oligomer; wherein the molar ratio of biphenyltetracarboxylic acid dianhydride to siloxane diamine monomer is 0.8:1;

[0033] Step 2:

[0034] S21: Disperse 4 g of 2,4-diaminophenol dihydrochloride in 60 g of N,N-dimethylacetamide, add 6 g of triethylamine, stir until no bubbles are generated in the system, add 4.2 g of hexafluorobenzene, 3.4 g of calcium hydride, and 3.8 g of cesium fluoride, heat to 75° C. in a nitrogen environment, and stir to react for 24 hours; after the reaction is completed, cool naturally, pour the reaction solution into deionized water, stir, wash, and dry to obtain a fluorine-modified diamine monomer;

[0035] S22: adding biphenyltetracarboxylic acid dianhydride to N,N-dimethylacetamide, adding fluorine-modified diamine monomer, heating to 60° C. in a nitrogen environment, reacting for 2 hours, to obtain anhydride-terminated fluorine-containing oligomer; wherein the molar ratio of biphenyltetracarboxylic acid dianhydride to the fluorine-modified diamine monomer is 1:0.8;

[0036] Step 3:

[0037] In a nitrogen environment, the molar ratio of anhydride to amine is controlled to be 1:1, and anhydride-terminated fluorine-containing oligomer and amine-terminated silicon-containing oligomer are mixed and reacted for 12 hours; acetic anhydride is used as a chemical imidization agent and triethylamine is used as a catalyst, and the reaction solution is obtained after stirring for 36 hours; the reaction solution is coated on a glass plate, and treated at 100°C for 2 hours, at 150°C for 2 hours, at 200°C for 2 hours, and at 250°C for 2 hours; it is put into deionized water, and demolding is performed to obtain a polyimide material.

[0038] Embodiment 2: A method for preparing a high heat-resistant and low-dielectric polyimide material, comprising the following steps:

[0039] Step 1:

[0040] S11: 4-aminostyrene was dispersed in tetrahydrofuran, an isopropanol solution of chloroplatinic acid (chloroplatinic acid concentration was 0.02 g / mL) was used as a catalyst, 1,1,3,3-tetramethyldisiloxane was added under an argon environment, the temperature was raised to 55° C. and the reaction was carried out for 3.5 hours, the solvent was evaporated, methanol was added to precipitate, and the siloxane diamine monomer was obtained by suction filtration and drying, wherein the molar ratio of 4-aminostyrene to 1,1,3,3-tetramethyldisiloxane was 2:1;

[0041] S12: adding biphenyltetracarboxylic acid dianhydride to N,N-dimethylacetamide, adding siloxane diamine monomer, heating to 70° C. in a nitrogen environment, reacting for 3 hours, to obtain an amine-terminated silicon-containing oligomer; wherein the molar ratio of biphenyltetracarboxylic acid dianhydride to siloxane diamine monomer is 0.8:1;

[0042] Step 2:

[0043] S21: Disperse 4 g of 2,4-diaminophenol dihydrochloride in 60 g of N,N-dimethylacetamide, add 6 g of triethylamine, stir until no bubbles are generated in the system, add 4.2 g of hexafluorobenzene, 3.4 g of calcium hydride, and 3.8 g of cesium fluoride, heat to 80° C. in a nitrogen environment, and stir to react for 27 hours; after the reaction is completed, cool naturally, pour the reaction solution into deionized water, stir, wash, and dry to obtain a fluorine-modified diamine monomer;

[0044] S22: adding biphenyltetracarboxylic acid dianhydride to N,N-dimethylacetamide, adding fluorine-modified diamine monomer, heating to 70° C. in a nitrogen environment, reacting for 3 hours, to obtain anhydride-terminated fluorine-containing oligomer; wherein the molar ratio of biphenyltetracarboxylic acid dianhydride to the fluorine-modified diamine monomer is 1:0.8;

[0045] Step 3:

[0046] In a nitrogen environment, the molar ratio of anhydride to amine is controlled to be 1:1, and anhydride-terminated fluorine-containing oligomer and amine-terminated silicon-containing oligomer are mixed and reacted for 18 hours; acetic anhydride is used as a chemical imidization agent and triethylamine is used as a catalyst, and the reaction solution is obtained after stirring for 42 hours; the reaction solution is coated on a glass plate, and treated at 100°C for 2 hours, at 150°C for 2 hours, at 200°C for 2 hours, and at 250°C for 2 hours; it is put into deionized water, and demolding is performed to obtain a polyimide material.

[0047] Embodiment 3: A method for preparing a high heat-resistant and low-dielectric polyimide material, comprising the following steps:

[0048] Step 1:

[0049] S11: 4-aminostyrene was dispersed in tetrahydrofuran, an isopropanol solution of chloroplatinic acid (chloroplatinic acid concentration was 0.02 g / mL) was used as a catalyst, 1,1,3,3-tetramethyldisiloxane was added under an argon environment, the temperature was raised to 55° C. for reaction for 4 h, the solvent was evaporated, methanol was added for precipitation, and the siloxane diamine monomer was obtained by suction filtration and drying, wherein the molar ratio of 4-aminostyrene to 1,1,3,3-tetramethyldisiloxane was 2:1;

[0050] S12: adding biphenyltetracarboxylic acid dianhydride to N,N-dimethylacetamide, adding siloxane diamine monomer, heating to 80° C. in a nitrogen environment, reacting for 4 hours, to obtain an amine-terminated silicon-containing oligomer; wherein the molar ratio of biphenyltetracarboxylic acid dianhydride to siloxane diamine monomer is 0.8:1;

[0051] Step 2:

[0052] S21: Disperse 4 g of 2,4-diaminophenol dihydrochloride in 60 g of N,N-dimethylacetamide, add 6 g of triethylamine, stir until no bubbles are generated in the system, add 4.2 g of hexafluorobenzene, 3.4 g of calcium hydride, and 3.8 g of cesium fluoride, heat to 85° C. in a nitrogen environment, and stir for 30 hours; after the reaction is completed, cool naturally, pour the reaction solution into deionized water, stir, wash, and dry to obtain a fluorine-modified diamine monomer;

[0053] S22: adding biphenyltetracarboxylic acid dianhydride to N,N-dimethylacetamide, adding fluorine-modified diamine monomer, heating to 80° C. in a nitrogen environment, reacting for 4 hours, to obtain anhydride-terminated fluorine-containing oligomer; wherein the molar ratio of biphenyltetracarboxylic acid dianhydride to the fluorine-modified diamine monomer is 1:0.8;

[0054] Step 3:

[0055] In a nitrogen environment, the molar ratio of anhydride to amine is controlled to be 1:1, and anhydride-terminated fluorine-containing oligomer and amine-terminated silicon-containing oligomer are mixed and reacted for 24 hours; acetic anhydride is used as a chemical imidization agent and triethylamine is used as a catalyst, and the reaction solution is obtained after stirring for 48 hours; the reaction solution is coated on a glass plate, and treated at 100°C for 2 hours, at 150°C for 2 hours, at 200°C for 2 hours, and at 250°C for 2 hours; it is put into deionized water, and demolding is performed to obtain a polyimide material.

[0056] Embodiment 4: A method for preparing a high heat-resistant and low-dielectric polyimide material, comprising the following steps:

[0057] Step 1:

[0058] S11: 4-aminostyrene was dispersed in tetrahydrofuran, an isopropanol solution of chloroplatinic acid (chloroplatinic acid concentration was 0.02 g / mL) was used as a catalyst, 1,1,3,3-tetramethyldisiloxane was added under an argon environment, the temperature was raised to 50° C. and reacted for 4 h, the solvent was evaporated, methanol was added to precipitate, and the siloxane diamine monomer was obtained by suction filtration and drying, wherein the molar ratio of 4-aminostyrene to 1,1,3,3-tetramethyldisiloxane was 2:1;

[0059] S12: adding biphenyltetracarboxylic acid dianhydride to N,N-dimethylacetamide, adding siloxane diamine monomer, heating to 65° C. in a nitrogen environment, reacting for 4 hours, to obtain an amine-terminated silicon-containing oligomer; wherein the molar ratio of biphenyltetracarboxylic acid dianhydride to siloxane diamine monomer is 0.8:1;

[0060] Step 2:

[0061] S21: Disperse 4 g of 2,4-diaminophenol dihydrochloride in 60 g of N,N-dimethylacetamide, add 6 g of triethylamine, stir until no bubbles are generated in the system, add 4.2 g of hexafluorobenzene, 3.4 g of calcium hydride, and 3.8 g of cesium fluoride, heat to 75° C. in a nitrogen environment, and stir to react for 24 hours; after the reaction is completed, cool naturally, pour the reaction solution into deionized water, stir, wash, and dry to obtain a fluorine-modified diamine monomer;

[0062] S22: adding biphenyltetracarboxylic acid dianhydride to N,N-dimethylacetamide, adding fluorine-modified diamine monomer, heating to 60° C. in a nitrogen environment, reacting for 3 hours, to obtain anhydride-terminated fluorine-containing oligomer; wherein the molar ratio of biphenyltetracarboxylic acid dianhydride to the fluorine-modified diamine monomer is 1:0.85;

[0063] Step 3:

[0064] In a nitrogen environment, the molar ratio of anhydride to amine is controlled to be 1:1, and anhydride-terminated fluorine-containing oligomer and amine-terminated silicon-containing oligomer are mixed and reacted for 12 hours; acetic anhydride is used as a chemical imidization agent and triethylamine is used as a catalyst, and the reaction solution is obtained after stirring for 48 hours; the reaction solution is coated on a glass plate, and treated at 100°C for 2 hours, at 150°C for 2 hours, at 200°C for 2 hours, and at 250°C for 2 hours; it is put into deionized water, and demolding is performed to obtain a polyimide material.

[0065] Embodiment 5: A method for preparing a high heat-resistant and low-dielectric polyimide material, comprising the following steps:

[0066] Step 1:

[0067] S11: 4-aminostyrene was dispersed in tetrahydrofuran, an isopropanol solution of chloroplatinic acid (chloroplatinic acid concentration was 0.02 g / mL) was used as a catalyst, 1,1,3,3-tetramethyldisiloxane was added under an argon environment, the temperature was raised to 55° C. for reaction for 3 h, the solvent was evaporated, methanol was added for precipitation, and the siloxane diamine monomer was obtained by suction filtration and drying, wherein the molar ratio of 4-aminostyrene to 1,1,3,3-tetramethyldisiloxane was 2:1;

[0068] S12: adding biphenyltetracarboxylic acid dianhydride to N,N-dimethylacetamide, adding siloxane diamine monomer, heating to 80° C. in a nitrogen environment, reacting for 2 hours, to obtain an amine-terminated silicon-containing oligomer; wherein the molar ratio of biphenyltetracarboxylic acid dianhydride to siloxane diamine monomer is 0.8:1;

[0069] Step 2:

[0070] S21: Disperse 4 g of 2,4-diaminophenol dihydrochloride in 60 g of N,N-dimethylacetamide, add 6 g of triethylamine, stir until no bubbles are generated in the system, add 4.2 g of hexafluorobenzene, 3.4 g of calcium hydride, and 3.8 g of cesium fluoride, heat to 75° C. in a nitrogen environment, and stir to react for 24 hours; after the reaction is completed, cool naturally, pour the reaction solution into deionized water, stir, wash, and dry to obtain a fluorine-modified diamine monomer;

[0071] S22: adding biphenyltetracarboxylic acid dianhydride to N,N-dimethylacetamide, adding fluorine-modified diamine monomer, heating to 60° C. in a nitrogen environment, reacting for 4 hours, to obtain anhydride-terminated fluorine-containing oligomer; wherein the molar ratio of biphenyltetracarboxylic acid dianhydride to the fluorine-modified diamine monomer is 1:0.9;

[0072] Step 3:

[0073] In a nitrogen environment, the molar ratio of anhydride to amine is controlled to be 1:1, and anhydride-terminated fluorine-containing oligomer and amine-terminated silicon-containing oligomer are mixed and reacted for 18 hours; acetic anhydride is used as a chemical imidization agent and triethylamine is used as a catalyst, and the reaction solution is obtained after stirring for 48 hours; the reaction solution is coated on a glass plate, and treated at 100°C for 2 hours, at 150°C for 2 hours, at 200°C for 2 hours, and at 250°C for 2 hours; it is put into deionized water, and demolding is performed to obtain a polyimide material.

[0074] Embodiment 6: A method for preparing a high heat-resistant and low-dielectric polyimide material, comprising the following steps:

[0075] Step 1:

[0076] S11: 4-aminostyrene was dispersed in tetrahydrofuran, an isopropanol solution of chloroplatinic acid (chloroplatinic acid concentration was 0.02 g / mL) was used as a catalyst, 1,1,3,3-tetramethyldisiloxane was added under an argon environment, the temperature was raised to 55° C. for reaction for 4 h, the solvent was evaporated, methanol was added for precipitation, and the siloxane diamine monomer was obtained by suction filtration and drying, wherein the molar ratio of 4-aminostyrene to 1,1,3,3-tetramethyldisiloxane was 2:1;

[0077] S12: adding biphenyltetracarboxylic acid dianhydride to N,N-dimethylacetamide, adding siloxane diamine monomer, heating to 75° C. in a nitrogen environment, reacting for 3 hours, to obtain an amine-terminated silicon-containing oligomer; wherein the molar ratio of biphenyltetracarboxylic acid dianhydride to siloxane diamine monomer is 0.8:1;

[0078] Step 2:

[0079] S21: Disperse 4 g of 2,4-diaminophenol dihydrochloride in 60 g of N,N-dimethylacetamide, add 6 g of triethylamine, stir until no bubbles are generated in the system, add 4.2 g of hexafluorobenzene, 3.4 g of calcium hydride, and 3.8 g of cesium fluoride, heat to 85° C. in a nitrogen environment, and stir to react for 28 h; after the reaction is completed, cool naturally, pour the reaction solution into deionized water, stir, wash, and dry to obtain a fluorine-modified diamine monomer;

[0080] S22: adding biphenyltetracarboxylic acid dianhydride to N,N-dimethylacetamide, adding fluorine-modified diamine monomer, heating to 70° C. in a nitrogen environment, reacting for 3 hours, to obtain anhydride-terminated fluorine-containing oligomer; wherein the molar ratio of biphenyltetracarboxylic acid dianhydride to the fluorine-modified diamine monomer is 1:0.95;

[0081] Step 3:

[0082] In a nitrogen environment, the molar ratio of anhydride to amine is controlled to be 1:1, and anhydride-terminated fluorine-containing oligomer and amine-terminated silicon-containing oligomer are mixed and reacted for 24 hours; acetic anhydride is used as a chemical imidization agent and triethylamine is used as a catalyst, and the reaction solution is obtained after stirring for 48 hours; the reaction solution is coated on a glass plate, and treated at 100°C for 2 hours, at 150°C for 2 hours, at 200°C for 2 hours, and at 250°C for 2 hours; it is put into deionized water, and demolding is performed to obtain a polyimide material.

[0083] Comparative Example 1: Polyimide was prepared without introducing siloxane, and other parameters were the same as those in Example 1.

[0084] Step 1:

[0085] Take 4g of dihydrochloric acid-2,4-diaminophenol and disperse it in 60g of N,N-dimethylacetamide, add 6g of triethylamine, stir until no bubbles are generated in the system, add 4.2g of hexafluorobenzene, 3.4g of calcium hydride, and 3.8g of cesium fluoride, heat to 75°C in a nitrogen environment, and stir to react for 24h; after the reaction is completed, cool naturally, pour the reaction solution into deionized water, stir, wash, and dry to obtain a fluorine-modified diamine monomer;

[0086] Step 2:

[0087] In a nitrogen environment, the molar ratio of anhydride to amine is controlled to be 1:1, and biphenyltetracarboxylic dianhydride and fluorine-modified diamine monomer are mixed and reacted for 12 hours; acetic anhydride is used as a chemical imidization reagent and triethylamine is used as a catalyst, and the reaction solution is obtained after stirring for 36 hours; the reaction solution is coated on a glass plate, and treated at 100°C for 2 hours, at 150°C for 2 hours, at 200°C for 2 hours, and at 250°C for 2 hours; it is put into deionized water, and demolding is performed to obtain a polyimide material.

[0088] Comparative Example 2: Polyimide was prepared without introducing fluorine element, and the other parameters were the same as those in Example 2.

[0089] Step 1:

[0090] 4-aminostyrene was dispersed in tetrahydrofuran, an isopropanol solution of chloroplatinic acid (chloroplatinic acid concentration was 0.02 g / mL) was used as a catalyst, 1,1,3,3-tetramethyldisiloxane was added under an argon environment, the temperature was raised to 55° C. for reaction for 3.5 hours, the solvent was evaporated, methanol was added for precipitation, and the siloxane diamine monomer was obtained by suction filtration and drying, wherein the molar ratio of 4-aminostyrene to 1,1,3,3-tetramethyldisiloxane was 2:1;

[0091] Step 2:

[0092] In a nitrogen environment, the molar ratio of anhydride to amine is controlled to be 1:1, and biphenyltetracarboxylic dianhydride and siloxane diamine monomers are mixed and reacted for 18 hours; acetic anhydride is used as a chemical imidization reagent and triethylamine is used as a catalyst, and the reaction solution is obtained after stirring for 42 hours; the reaction solution is coated on a glass plate, and treated at 100°C for 2 hours, at 150°C for 2 hours, at 200°C for 2 hours, and at 250°C for 2 hours; it is put into deionized water, and demolding is performed to obtain a polyimide material.

[0093] Comparative Example 3: After mixing the siloxane diamine monomer and the fluorine-modified diamine monomer, random copolymerization is carried out with biphenyltetracarboxylic dianhydride. The other parameters (including the fluorine and silicon contents in the polyimide) are the same as those in Example 3.

[0094] Step 1:

[0095] 4-aminostyrene was dispersed in tetrahydrofuran, an isopropanol solution of chloroplatinic acid (chloroplatinic acid concentration was 0.02 g / mL) was used as a catalyst, 1,1,3,3-tetramethyldisiloxane was added under an argon environment, the temperature was raised to 55° C. for reaction for 4 h, the solvent was evaporated, methanol was added for precipitation, suction filtration and drying were performed to obtain a siloxane diamine monomer, wherein the molar ratio of 4-aminostyrene to 1,1,3,3-tetramethyldisiloxane was 2:1;

[0096] Step 2:

[0097] Take 4g of dihydrochloric acid-2,4-diaminophenol and disperse it in 60g of N,N-dimethylacetamide, add 6g of triethylamine, stir until no bubbles are generated in the system, add 4.2g of hexafluorobenzene, 3.4g of calcium hydride, and 3.8g of cesium fluoride, heat to 85°C in a nitrogen environment, and stir to react for 30h; after the reaction is completed, cool naturally, pour the reaction solution into deionized water, stir, wash, and dry to obtain a fluorine-modified diamine monomer;

[0098] Step 3:

[0099] The siloxane diamine monomer and the fluorine-modified diamine monomer are mixed to obtain a diamine monomer mixture; in a nitrogen environment, the molar ratio of the anhydride to the amine is controlled to be 1:1, biphenyltetracarboxylic dianhydride is added to the mixture for a reaction for 24 hours, acetic anhydride is used as a chemical imidization reagent, triethylamine is used as a catalyst, and after stirring for 48 hours, a reactant solution is obtained; the mixture is treated at 100° C. for 2 hours, at 150° C. for 2 hours, at 200° C. for 2 hours, and at 250° C. for 2 hours; the mixture is placed in deionized water, and demolding is performed to obtain a polyimide material.

[0100] Experiment: The polyimide materials prepared in Examples 1 to 6 and Comparative Examples 1 to 3 were tested, and the thickness of the polyimide materials was controlled to be 20 μm. The experimental results are shown in the following table.

[0101] Dielectric performance test: Copper was evaporated on both sides of the sample by a vacuum coating machine, and the copper plating thickness on one side was 10nm; the dielectric impedance-thermal current comprehensive analyzer was used for testing, the test frequency was 1MHz, and the test temperature was 25-30℃.

[0102] Thermal decomposition temperature: The prepared polyimide film was tested using a thermogravimetric analyzer. The experimental conditions were as follows: in an environment where nitrogen was continuously introduced, the temperature was raised from room temperature to 800°C at a rate of 20°C / min. The mass of the sample was 5 mg. The temperature at which the thermal weight loss was 5% was recorded as Td. 5％ .

[0103] Linear thermal expansion coefficient: The test was conducted using a thermomechanical analyzer; the test temperature range was 30-300°C, the atmosphere was air, and the sample size was 4×0.5 cm. The data between 50 and 200°C during the heating process were taken, and the linear thermal expansion coefficient (CTE) was obtained based on the slope of the curve.

[0104] project Dielectric constant (at 1MHz) <![CDATA[Td 5％ (℃)]]> CTE(ppm / ℃) Example 1 2.44 563 20.24 Example 2 2.46 567 20.46 Example 3 2.47 565 20.37 Example 4 2.42 571 19.82 Example 5 2.40 576 19.74 Example 6 2.38 582 19.51 Comparative Example 1 2.57 554 23.23 Comparative Example 2 2.66 547 23.42 Comparative Example 3 2.51 558 21.15

[0105] Conclusion: The polyimide prepared by the present invention not only has good heat resistance, but also has a lower dielectric constant and linear thermal expansion coefficient. The data of Example 1 and Comparative Example 1 show that the introduction of siloxane into the main chain of the polyimide material can effectively improve the heat resistance and dielectric properties; the data of Example 2 and Comparative Example 2 show that the introduction of fluorine-containing groups into the side chain of the polyimide material can effectively improve the heat resistance and dielectric properties; the data of Example 3 and Comparative Example 3 show that compared with random copolymerization, the polyimide material prepared by block copolymerization has better performance.

[0106] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a high heat-resistant and low-dielectric polyimide material, characterized in that: The following steps are involved: Step 1: 4-aminostyrene is dispersed in tetrahydrofuran, an isopropanol solution of chloroplatinic acid is used as a catalyst, 1,1,3,3-tetramethyldisiloxane is added under an argon environment, the temperature is raised to 50-55° C. for reaction for 3-4 hours, the solvent is evaporated, methanol is added for precipitation, and the siloxane diamine monomer is obtained by suction filtration and drying; 4-aminostyrene and 1,1,3,3-tetramethyldisiloxane are reacted in a molar ratio of 2:1; Add biphenyltetracarboxylic acid dianhydride to N,N-dimethylacetamide, add siloxane diamine monomer, raise the temperature to 60-80°C under nitrogen environment, react for 2-4 hours, and obtain amine-terminated silicon-containing oligomer; react siloxane diamine monomer with biphenyltetracarboxylic acid dianhydride at a molar ratio of 1:(0.5-0.95); Step 2: Disperse 2,4-diaminophenol dihydrochloride in N,N-dimethylacetamide, add triethylamine, stir until no bubbles are generated in the system, add hexafluorobenzene, calcium hydride, and cesium fluoride, heat to 75-85° C. in a nitrogen environment, and stir for 24-30 hours; after the reaction is completed, cool naturally, pour the reaction solution into deionized water, stir, wash, and dry to obtain a fluorine-modified diamine monomer; wherein the amount of each component, by weight, is 3.5-4.2 parts of 2,4-diaminophenol dihydrochloride, 50-60 parts of N,N-dimethylacetamide, 5-8 parts of triethylamine, 4.2-4.8 parts of hexafluorobenzene, 3-3.5 parts of calcium hydride, and 3.6-4 parts of cesium fluoride; Add biphenyltetracarboxylic acid dianhydride to N,N-dimethylacetamide, add fluorine-modified diamine monomer, heat to 60-80°C in a nitrogen environment, react for 2-4 hours, and obtain anhydride-terminated fluorine-containing oligomer; biphenyltetracarboxylic acid dianhydride and fluorine-modified diamine monomer react at a molar ratio of 1:(0.5-0.95); Step 3: In a nitrogen environment, the molar ratio of anhydride to amine is controlled to be 1:1, and the anhydride-terminated fluorine-containing oligomer and the amine-terminated silicon-containing oligomer are mixed and reacted for 12 to 24 hours; acetic anhydride is used as a chemical imidization reagent and triethylamine is used as a catalyst, and the reaction solution is obtained after stirring for 36 to 48 hours; the reaction solution is coated on a glass plate, and after heat treatment, it is placed in deionized water, and demolding is performed to obtain a polyimide material.

2. The method for preparing a high heat-resistant and low-dielectric polyimide material according to claim 1, characterized in that: In step 3, the heat treatment method is to treat at 100°C for 1~2h, treat at 150°C for 1~2h, treat at 200°C for 1~2h, and treat at 250°C for 1~2h.

3. The polyimide material prepared by the method for preparing a high heat-resistant and low dielectric polyimide material according to any one of claims 1 to 2.

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